Fuses have found wide applications in industry and the home and are designed to prevent an excessive overload of current from damaging electrical equipment. In the most basic form an electrical fuse comprises a fusible link or fuse element connected between electrical conducting members which are intended to be inserted in series with the circuit serving the electrical equipment. In operation the fuse element functions in response to an excessive amount of current by opening the circuit to prevent damage of the equipment.
More advanced types of fuses have mechanical operating apparatus combined with fuse elements to effect the opening of a protected electrical circuit. For example, one such type of fuse device utilizes a disk contact structure to open the electrical circuit. The disk contact is controlled by the melting and voluminous expansion of a temperature sensitive member responding to an excessive amount of electrical current. Other types of fuse devices employ spring apparatus in combination with a fuse element to form a contact structure that operates to open the protected circuit when excessive current melts the fuse element. A problem with these types of fuse devices is that the mechanical operating apparatus and fuse elements are positioned within an electrical conducting casing or housing that prevents a visual inspection as to the operative or inoperative state of the fuse.
Alarm indicating fuses have been disclosed in the prior art and are designed to provide a visual indication when the fuse element operates to open the protected electrical circuit. Such a fuse device typically comprises a pair of electrical conducting members each located on the end of an insulative housing having a fuse element positioned therein. The fuse element coupled to one of the electrical conducting members is connected through a spring member located outside the insulative housing to the other electrical conducting member. An electrical path extends from the one electrical conducting member through the fuse element and spring member to the other electrical conducting member. Excess current flowing through the path opens the fuse element to interrupt the protected electrical circuit and release the spring member to visibly indicate the inoperative state of the fuse. A problem arises with this type of fuse device in that the conducting spring member adds resistance in the electrical path and increases the temperature of the fuse device thereby limiting use to specific applications.
Accordingly, a need exists for an alarm indicating fuse for both low and high current electrical circuit applications. A need also exists for an alarm indicating fuse designed to both lower the resistance of the electrical path and the total wattage output of the fuse to thereby improve use for both low and high current circuit applications.